• Tiny mite triggers domino effect in the

    From ScienceDaily@1:317/3 to All on Tue Mar 8 21:30:38 2022
    Tiny mite triggers domino effect in the high Andes
    Pumas, condors and grasslands impacted after mange wipes out park's
    vicun~as

    Date:
    March 8, 2022
    Source:
    University of California - Davis
    Summary:
    What happens when a disease disrupts a protected ecosystem so
    forcefully that cascading consequences are felt by nearly all
    wildlife and plants within it? A study examines how the mange
    outbreak among vicun~as restructured tightly linked food-chain
    interactions that were previously driven by pumas.



    FULL STORY ==========================================================================
    The idea of food chains and food webs in the animal kingdom is simple:
    Remove a link or thread, and the system is broken. But nature is complex,
    and it's not always clear how the absence of one species may impact
    others.


    ========================================================================== Other times, the connection is devastatingly clear.

    Argentina's wild vicun~as are close relatives of alpacas and llamas. For decades, vicun~as, pumas and condors have been intrinsically connected, sustaining the high Andes ecosystem of Argentina's San Guillermo National
    Park: Vicun~as grazed the grass. Pumas preyed extensively upon the
    vicun~a. And condors depended on the pumas' leftovers.

    That is, until recent years, when one by one, each of these relationships unraveled across the landscape after a mange outbreak decimated the
    park's vicun~a population in less than five years.

    What happens when a disease disrupts a protected ecosystem so forcefully
    that cascading consequences are felt by nearly all wildlife and plants
    within it? A study published in the journalEcology Lettersexamines how
    the mange outbreak among vicun~as restructured tightly linked food-chain interactions that were previously driven by pumas, also called mountain
    lions or cougars.



    ========================================================================== Remote chances It also illustrates how even remote parks are not fully
    safe from human impacts. A recent UC Davis study indicates the mange
    outbreak stemmed from domestic llamas introduced to private lands outside
    the park.

    "This preserve is about as remote as you can get, with very little
    human interaction, and yet it is still not safe from human activities
    occurring hundreds of miles away," said co-leading author Justine Smith,
    as assistant professor with the UC Davis Department of Wildlife, Fish and Conservation Biology. "Pathogens can take hold quickly, leaving animals
    with little time to respond or adapt. We might see unintended consequences
    that we should be preparing for when managing at-risk populations
    of wildlife." Chain reactions Sarcoptic mange is a highly contagious
    disease in which parasitic mites burrow under the skin, making it too
    painful to move and forage. Many animals starve or become easy prey.



    ==========================================================================
    When the study's authors began to see mange rapidly spread through the
    park, they were already studying pumas and vicun~as there. They switched
    gears to study the chain reaction of the disease outbreak in 2015.

    They tracked condors, pumas and vicun~as with GPS devices and used a combination of on-the-ground vegetation surveys and remote sensing data
    from satellites to analyze landscape changes. Researchers and field
    technicians also collected data on vicun~a densities, mange prevalence
    and puma hunting behavior.

    Their findings show that introduced disease can cause rapid and
    catastrophic changes to wildlife populations and their ecosystems.

    "The changes to the landscape were really evident even as we were
    collecting the data to confirm these patterns," said co-leading author
    Julia Monk, a Ph.D.

    candidate at Yale School of the Environment. "We went from seeing condors
    daily to going months on end without encountering them, and the open
    plains that were practically bare when I started working in the park
    had exploded with vegetation by my next field season. " Tiny mite,
    big changes Before the outbreak, pumas had been the biggest threat to
    vicun~as, whose grazing strategy was designed around avoiding them. But
    the tiny mite turned out to be the much bigger threat.

    The study found that vicun~as plummeted from more than 17 individuals per square kilometer before the outbreak, to 1 per square kilometer by 2020.

    Condors, which were the primary scavengers and abundant in the system, eventually left the park entirely when their food source disappeared.

    The impact on pumas, the park's top carnivore, is less clear, as tracking collars were only operational through 2017. The authors know that at
    least one puma they monitored starved to death, though puma sightings
    remained common throughout the study. Anecdotally, the authors also
    observed animals switching prey to smaller items, such as an instance
    where a puma was hunting a tuco- tuco, a small rodent.

    Range anxiety The changes among the animals also brought massive change
    to the landscape.

    Bare ground became covered in grasses over huge expanses visible from
    space.

    Vegetation increased up to 900% in areas where vicun~as preferentially
    foraged to avoid becoming puma prey. There is some concern this growth
    could spark a population explosion of European hares, although more
    research is needed to verify those concerns.

    "We don't really know how or if these systems will recover," Smith
    said. "Will they return to the system we knew, or will a new balance
    emerge from these dynamics? It's hard to predict." The scientists
    say the study also highlights the importance of baseline monitoring,
    basic research and supporting the capacity of scientists outside the
    United States.

    "Continuing to support our colleagues in Argentina who have worked for
    decades to understand and protect this unique system will be vital for
    tracing the continuing effects of the disease and for promoting the
    ecosystem's recovery," Monk said.

    Additional co-authoring institutions include Fundacio'n Rewilding
    Argentina, INIBIOMA-CONICET in Argentina, University of Wisconsin-Madison, Smithsonian National Zoo and Conservation Biology Institute, Universidad Nacional de La Plata in Argentina, and UC Berkeley.

    The research was supported by the National Geographic Society, Yale
    University, UC Berkeley, CONICET and other conservation organizations.


    ========================================================================== Story Source: Materials provided by
    University_of_California_-_Davis. Original written by Kat Kerlin. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Julia D. Monk, Justine A. Smith, Emiliano Donadi'o, Paula L. Perrig,
    Ramiro D. Crego, Martin Fileni, Owen Bidder, Sergio A. Lambertucci,
    Jonathan N. Pauli, Oswald J. Schmitz, Arthur D. Middleton. Cascading
    effects of a disease outbreak in a remote protected area. Ecology
    Letters, 2022; DOI: 10.1111/ele.13983 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220308102837.htm

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